Conventionally, as disclosed in Patent Document 1 identified below, there was known a valve timing control apparatus including a locking mechanism for restraining a relative rotational phase of a driven-side rotor relative to a drive-side rotor and a restricting mechanism provided at a different position along the direction of relative rotation than the locking mechanism and configured for restricting a relative rotational movement within a predetermined range. The locking mechanism includes a locking member provided in the drive-side rotor and a locking groove defined in the driven-side rotor for receiving and retaining the locking member projecting therein. Further, the restricting mechanism includes a restricting member disposed in the drive-side rotor and a restricting groove defined as an elongate slot in the driven-side rotor for receiving the restricting member projecting therein.
With the above-described technique, only with execution of a controlling operation to the angle advancing side or angle retarding side, the restraint of the relative rotational phase by the locking mechanism can be released and then the relative rotational phase can be restricted within the predetermined range by means of the restricting mechanism. That is, after appropriate start-up of the internal combustion engine in the phase restrained by the locking mechanism, even in a situation when precision phase control is difficult due to the work fluid being at a low temperature, the relative rotational phase can be restricted to a predetermined phase by means of the restricting mechanism.
Patent Document 2 identified also below discloses a valve timing control apparatus including an angle advancement restricting mechanism for restricting displacement of the relative rotational phase to the angle advancing side from a predetermined phase between the most advanced angle phase and the most retarded angle phase, an angle retardation restricting mechanism for restricting displacement of the relative rotational phase from the predetermined phase to the angle retarding side, and hydraulic control valves provided exclusively for controlling the work fluid to act on these mechanisms respectively. The angle advancement restricting mechanism and the angle retardation restricting mechanism each includes a restricting member and a restricting groove into which the restricting member can project. Further, the restricting groove of the angle advancement restricting mechanism has an increased depth at its position corresponding to the predetermined phase, so that when the restricting member enters this increased depth portion, the relative rotational phase can be restrained to the predetermined phase.
With the above-described technique, through controlling of the hydraulic control valves, the relative rotational phase can be restrained to the predetermined phases in a reliable manner at the time of stopping of the internal combustion engine or at the time of next start-up thereof.